// 基于一下代码完成下面四个练习
const { toUpper } = require('lodash')
const fp = require('lodash/fp')

// 数据
// horsepower 马力，dollar_value 价格，in_stock 库存
const cars = [
    { name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true },
    { name: 'Spyker C12 Zagato', horsepower: 650, dollar_value: 648000, in_stock: false },
    { name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false },
    { name: 'Aston Martin One-77', horsepower: 750, dollar_value: 1850000, in_stock: true },
    { name: 'Pagani Huayra', horsepower: 700, dollar_value: 1300000, in_stock: false },
]

// 1.使用函数组合fp.flowRight()重新实现这个函数
let isLastInstock = function(cars) {
    // 获取最后一条数据
    let last_car = fp.last(cars)
        // 获取最后一条数据的in_stock属性值
    return fp.prop('in_stock', last_car)
}
console.log('题目1答案：' + isLastInstock(cars));
let isLastInstock1 = fp.flowRight(fp.prop('in_stock'), fp.last)
console.log('练习1答案：' + isLastInstock1(cars));

// 2.使用fp.flowRight()、fp.prop()和fp.first()获取第一个car的name
let firstName = fp.flowRight(fp.prop('name'), fp.first)
console.log('练习2答案：' + firstName(cars));

// 3.使用帮助函数_average重构averageDollarValue,使用函数组合的方式实现
let _average = function(xs) {
        return fp.reduce(fp.add, 0, xs) / xs.length
    } //<-无需改动

let averageDollarValue = function(cars) {
    let dollar_values = fp.map(function(cars) {
        return cars.dollar_value
    }, cars)
    return _average(dollar_values)
}
console.log('题目3答案：' + averageDollarValue(cars));
let comAverageDollarValue = fp.flowRight(_average, fp.map('dollar_value'));
console.log('练习3答案：' + comAverageDollarValue(cars));
// 4.使用flowRight写一个sanitizeNames()函数，返回一个下划线连接的小写字符串，把数组中的name转换为这种形式：
// 例如：sanitizeNames(['Hello World'])=>['hello_word']
let _underscore = fp.replace(/\W+/g, '_') //<--无需改动，并在sanitizeNames中使用它
let sanitizeNames = fp.flowRight(_underscore, fp.map(fp.toLower));
console.log('练习4答案：' + sanitizeNames(['Hello World']));